Transceive surface coil array for magnetic resonance imaging and spectroscopy

Abstract

A surface coil array comprises a surface coil support and an arrangement of non-overlapping magnetically decoupled surface coils mounted on the support. The surface coils encompass a volume into which a target to be imaged is placed. Magnetic decoupling circuits act between adjacent surface coils. Impedance matching circuitry couples the surface coils to conventional transmit and receive components.

1 . A surface coil array comprising: 
 a plurality of spaced surface coils arranged about a volume; and    magnetic decoupling circuits acting between said surface coils.    
     
     
         2 . A surface coil array according to  claim 1  wherein magnetic decoupling circuits act between adjacent surface coils.  
     
     
         3 . A surface coil array according to  claim 2  wherein said magnetic decoupling circuits are purely capacitive.  
     
     
         4 . A surface coil array according to  claim 3  wherein the capacitive reactance of each magnetic decoupling circuit is equal to the mutual inductive reactance between adjacent surface coils.  
     
     
         5 . A surface coil array according to  claim 4  wherein each magnetic decoupling circuit comprises a single capacitor.  
     
     
         6 . A surface coil array according to  claim 4  wherein said surface coils are generally equally spaced about said volume.  
     
     
         7 . A surface coil array according to  claim 5  further comprising a dielectric support on which said surface coils are mounted.  
     
     
         8 . A surface coil array according to  claim 7  further comprising dielectric loss reducing elements distributed about said surface coils.  
     
     
         9 . A surface coil array according to  claim 8  wherein said dielectric loss reducing elements are low-loss lumped capacitors.  
     
     
         10 . A surface coil array according to  claim 4  further comprising baluns coupled to said surface coils.  
     
     
         11 . A surface coil array according to  claim 10  wherein said baluns are impedance matched to feed network circuitry coupled thereto.  
     
     
         12 . A surface coil array according to  claim 11  wherein said baluns are impedance matched to 50Ω component-based feed network circuitry.  
     
     
         13 . A surface coil array according to  claim 10  further comprising a feed network coupled to said baluns and communicating with said surface coils.  
     
     
         14 . A surface coil array according to  claim 13  wherein said baluns are balanced and impedance matched to said feed network.  
     
     
         15 . A surface coil array according to  claim 14  wherein said feed network comprises conventional transmit and receive components.  
     
     
         16 . A surface coil array according to  claim 15  wherein said conventional transmit and receive components comprise 50Ω preamplifiers and low cost radio frequency (RF) power amplifiers.  
     
     
         17 . A surface coil array according to  claim 16  wherein said feed network further comprises a 50Ω coaxial cable connecting said baluns to said feed network.  
     
     
         18 . A surface coil array according to  claim 13  wherein said baluns are configured to provide transmit signals generated by said feed network to said surface coils for transmit operation and to provide receive signals received by said surface coils to said feed network for receive operation.  
     
     
         19 . A surface coil array according to  claim 18  wherein said feed network comprises conventional transmit and receive components.  
     
     
         20 . A surface coil array according to  claim 19  wherein said conventional transmit and receive components comprise 50Ω preamplifiers and low cost RF power amplifiers.  
     
     
         21 . A surface coil array according to  claim 13  wherein said baluns are configured to condition said surface coil array to a receive-only mode, in said receive-only mode, said baluns isolating said surface coils from said feed network when said feed network generates transmit signals.  
     
     
         22 . A surface coil array according to  claim 21  wherein said feed network comprises conventional transmit and receive components.  
     
     
         23 . A surface coil array according to  claim 22  wherein said conventional transmit and receive components comprise 50Ω preamplifiers and low cost power amplifiers.  
     
     
         24 . A surface coil array according to  claim 4  wherein a magnetic decoupling circuit acts between each adjacent pair of surface coils.  
     
     
         25 . A surface coil array according to  claim 4  wherein said surface coils are arranged in sets, magnetic decoupling circuits acting between adjacent pairs of surface coils in each set.  
     
     
         26 . A surface coil array according to  claim 11  wherein said feed network circuitry includes a separate low power transmitter for each surface coil.  
     
     
         27 . A surface coil array according to  claim 18  wherein said feed network includes a separate low power transmitter for each surface coil.  
     
     
         28 . A surface coil array according to  claim 11  wherein receive signals received by said surface coils bypass said feed network circuitry.  
     
     
         29 . A surface coil array comprising: 
 a surface coil support;    a plurality of generally evenly spaced surface coils mounted on said support and surrounding a volume into which a target to be imaged is placed; and    capacitive decoupling circuitry acting between said surface coils to reduce magnetic coil-to-coil coupling.    
     
     
         30 . A surface coil array according to  claim 29  further comprising a feed network and impedance matching circuitry acting between said feed network and each of said surface coils.  
     
     
         31 . A surface coil array according to  claim 30  wherein said feed network comprises conventional transmit and receive components.  
     
     
         32 . A surface coil array according to  claim 31  wherein said conventional transmit and receive components comprise 50Ω preamplifiers and low cost RF power amplifiers.  
     
     
         33 . A surface coil array according to  claim 31  wherein said impedance matching circuitry is configured to provide transmit signals generated by said feed network to said surface coils for transmit operation and to provide receive signals received by said surface coils to said feed network for receive operation.  
     
     
         34 . A surface coil array according to  claim 33  wherein said conventional transmit and receive components comprise 50Ω preamplifiers and low cost RF power amplifiers.  
     
     
         35 . A surface coil array according to  claim 30  wherein said impedance matching circuitry comprising a λ/4 lattice balun associated with each surface coil.  
     
     
         36 . An RF resonator comprising: 
 a surface coil array including an arrangement of non-overlapping magnetically decoupled surface coils encompassing a volume; and    a feed network coupled to said surface coil array, said feed network at least receiving signals received by said surface coils during imaging of a target within said volume.    
     
     
         37 . An RF resonator according to  claim 36  wherein said feed network comprises conventional 50Ω transmit and receive components.  
     
     
         38 . An RF resonator according to  claim 37  wherein said surface coil array comprising impedance matching circuitry acting between each surface coil and said feed network.  
     
     
         39 . An RF resonator according to  claim 38  wherein said feed network provides transmit signals to said surface coils via said impedance matching circuitry.  
     
     
         40 . A surface coil array comprising: 
 a surface coil support; and    an arrangement of non-overlapping magnetically decoupled surface coils mounted on said support and encompassing a volume into which a target to be imaged is placed.    
     
     
         41 . A surface coil array according to  claim 40  wherein each of said surface coils is generally identical.  
     
     
         42 . A surface coil array according to  claim 41  wherein said surface coils are of varying shape and/or size.  
     
     
         43 . A surface coil array according to  claim 42  wherein said surface coils are grouped into sets, the surface coils in each set being magnetically decoupled independent of other sets.  
     
     
         44 . A surface coil array according to  claim 43  wherein said surface coils receive transmit signals from at least one radio frequency transmitter.  
     
     
         45 . A surface coil array according to  claim 44  wherein said surface coils receive transmit signals from a single transmitter.  
     
     
         46 . A surface coil array according to  claim 45  wherein each surface coil receives transmit signals from an associated transmitter.